Process for producing artificial cryolite free from iron, from aluminumsalt solutions containing iron



Patented Dec. l, 1925. i

UNITED STATES PATENT OFFICE.

HEINRICH SPECEKETER, F GRIE$HEIM-ON-THE-MAIN, GERMANY, ASSIGND-R, 'ro CHEMISCHE FABRIK GRIESHEIM-ELEKTRON, OF-FRANKFORT-ON-THE-MAIN, GER- MANY.

PROCESS FOR PRODUCING ARTIFICIAL CRYOLITE FREE FROM IRON, FROM ALUMINUM- SALT SOLUTIONS CONTAINING IRON.

No Drawing. Application filed January 10, 1925. Serial No. 1,706.

To all whom it may concern: fluorides from certain solutions containing Be it known that I, HEINRICH SPECKETER, hydrofluoric salts, for instance mother liqa citizen of Germany, and residing at Griesuors from the production of simple or comheim-on-the-Main, Germany, have invented plcx fluorine compounds. 65 certain new and useful Improvements in The acid filtrate from the chiolite, contain- Processes for Producing Artificial Cryolite ing iron, may again be saturated with alumi- Free from Iron, from Aluminum-Salt Solunum by using it for extracting potters earth tions Containing Iron, of which the follow- (preferably calcined) and again producing ing is a specification. chiolite free from iron from which artificial 0o The present invention relates to the procryolitc may be obtained in the above deduction of artificial cryolitc, free from iron, scribed manner. In this connection, it is refrom aluminum salt solutions containing markable that the parts of fluorides remainiron. I have found that under certain coning in the strong hydrochloric solution in ditions sodium chiolite free from iron can be the form of complex fluorine compounds do 85 obtained from above solutions, which chionotreact with the silicic acid of the potters lite may be combined with sodium fluoride earth, but,in the formation ofchiolite or to form artificial cryolite. cryolite respectively.

The production of sodium chiolite may be Now I have found that the cryolite thus i d t in th followi g ann Hot obtained may again be transformed to chio- 70 hydrofluoric acid is run while stirring, into lite and thelatter may anew be used for the an aluminum chloride solution heated to 60 above mentioned cleansing operation by C. at least, the quantity of the hydrofluoric hcatmg the cryolite with mineral acid, for acid being calculated in such a manner that instance hydrochloric acid with or without at most 9 molecules of hydrofluoric acid are the fiddltlOIl Of aluminum salts. \Vhen us- 75 present to one nolecule of aluminum oxid, 111g aluminum salts chiolite is continuous y The aluminum chloride solution may conformed w; When using acid alone the tain a considerable proportion of ferric quantity 0f the chiolite remains unchanged. chloride. On adding a hot saturated solu- I 1 im2 tion of alkali metal chloride, for instance 1- Pr c ss of producing artificial cryolite 80 common salt in the proportion of at least 3 free from iron from aluminum salt solutions molecules of sodiu hlorid to on olecontaining iron, which process comprises cule of al inu oxid, odi hi lit i adding to the said solutions While stirring 9 formed, molecules of hydrofluoric acid at most and 3 -I have found that th hi lit th obmolecules of alkali metal chloride at least to 85 tained is free from iron and that its separa- 9 m e f luminum oxide and treat- I tion may be facilitated by continuing the mg 111 the presence of water the precipitate stirring, before the sodium-chloride is added, thus Obtalned h alkall metal fluoride. for some time, say half an hour. 2. Process of producing artificial cryolite Furthermore I have found that on mixing free from iron from aluminum salt solutions 90 the chiolite, after separation and washing, containing 1ron ,wh1ch process comprises addwith pure sodiumfluoride-in the proportion g t0 the d solutions While irring 9 of 3 molecules of sodium fluoride to 2 atoms molecules of I YQ i at most, 0011- of aluminum in the chiolite, with or witht1 nuing the st1rr1ng of the mixture for some out the addition of some water, and filtering t1me, adding 3 molecules of alkali metal as off th crystallized mass, an aggregation bechloride at least to one molecule of alumi-' tween chiolite and sodium fluoride has taken m m d, nd trea lng in the presence of place and the corresponding artificial cryo- Water the preclpitate thus obtained with allitc free from iron has been formed. kali metal fluoride.

This peculiar affinity or aggregation may 3. Process of producing artificial cyrolpq 6 also be used for extracting and recovering lite free from iron from aluminum salt solu 1n the form of chiolite the rest of dissolved tions contalnmg iron, which process comprises adding to the said solutions while stirring 9 molecules of hydrofluoric acid at most and 3 molecules of alkali metal chloride at least to one molecule of aluminum oxid, mixing the precipitate thus obtained with Water and alkali metal fluoride to form a moist paste of salts, and letting the mass react.

4. Process for producing artificial cryolite, free from iron, from aluminum salt solutions containing iron, which process comprises extracting potters earth with acid mother liquors obtained in the production of chiolite, addin to the aluminum salt solutions thus obtalned While stiring 9 molecules of hydrofluoric acid at most and 3 molecules of alkali metal chloride at least I to one molecule of aluminum oxid, and treating in the presence of water the precipitate thus obtained with alkali metal fluoride.

5. Process of producing artificial cryolite free from iron from aluminum salt solutions containing iron, which process comprises adding to the solutions while stirring 9 molecules of hydrofluoric acid at most and 3 molecules of alkali metal chloride at least to one molecule of aluminum oxid, and treating the precipitate thus obtained with the mother liquors containing alkali metal fluoride obtained in the production of simple or complex fluorine compounds.

In testimony whereof I aflix my signature.

HEINRICH SPECKETER. 

